Lucy in the Sky.

“Lucy in the Sky with Diamonds” is a song credited to Lennon that appears on the Beatles’ 1967 album Sgt. Pepper’s Lonely Hearts Club Band. It was started by John Lennon, then Paul McCartney contributed to it in a songwriting session. Lennon’s son Julian inspired the song with a nursery school drawing he called “Lucyin the sky with diamonds”.

“Sgt. Pepper’s Lonely Hearts Club Band is the eighth studio album by English rock band the Beatles. Released on 26 May 1967 in the United Kingdom and 2 June 1967 in the United States, it was an immediate commercial and critical success, spending 27 weeks at the top of the UK albums chart and 15 weeks at number one in the US. On release, the album was lauded by the vast majority of critics for its innovations in music production, songwriting and graphic design, for bridging a cultural divide between popular music and legitimate art, and for providing a musical representation of its generation and the contemporary counterculture. It won four Grammy Awards in 1968, including Album of the Year, the first rock LP to receive this honour.”
(From Wikipedia).